Re: "Magnet tamper" for surface mount contact?

["Crash Gordon" <webmaster@xxxxxxxxxxxxxxxxxxxxx>]

You could always put another switch under the magnet and put that circuit on
a 24 hr zone...like a recessed switch mounted under the mounted
magnet...you'd need an ugly door cord though.


"Bill" <bill190nospam@xxxxxxxxx> wrote in message
news:3pim8eFaickcU1@xxxxxxxxxxxxxxxxx
| I've read the specs on the balanced contacts, but don't see anything about
| how just unscrewing the magnet would trip an alarm?
|
| I see that placing an additional magnet up by the contact would upset the
| magnetic balance and then trip the alarm, or unscrewing the magnet and
then
| moving it closer to the contact and taping it in place would trip the
| alarm....
|
| But I don't see where unscrewing the magnet and keeping it the same
distance
| from the contact would cause an alarm.
|
| I seem to recall that there were contacts on a UL grade AA system which
had
| covers over the magnets. The contact and magnet were both about 2 inches
by
| 4 or 5 inches and 2 inches deep. Both the contact and magnet had covers
with
| tampers. If you removed the cover over the magnet, I think it would either
| drop the magnet away from the contact or place a barrier between the
magnet
| and the contact. Attempting to remove the magnet from the door by removing
| the cover would cause an alarm.
|
| I never installed any of these or had need to service them, so don't know
if
| this is true or not. I was told that attempting to remove the cover from
the
| contact or the magnet would trip the alarm. These also had three wire
| connections. (For UL system...)
|
|
|
| "Jackcsg" wrote in message
| > What you're looking for is called a "BMS" (Balanced Magnetic Switch) I
| > believe both Ademco, and Sentrol have a model for the application.
| >
| > "Bill" wrote in message
| >
| > > Is there a surface mount contact which has some sort of tamper device
if
| > the
| > > magnet is unscrewed from the door? Manufacturer? Model number?
| > >
| > > This would prevent the situation where there is a door which opens
out,
| > > there is a surface mount contact on the door frame, a surface mount
| magnet
| > > on the door - then intruder attaches magnet to above contact in some
| > manner,
| > > unscrews magnet from door, then opens door outwards.
| > >
| > > So unscrewing the magnet from the door or unscrewing the covering over
| the
| > > magnet to then unscrew the magnet from the door would trip the
| contact...
| > >
| > > FYI - This is when the intruder gains access through the ceiling or
| wall,
| > > but then exits through a door.
| > >
| > >
| >
| >
|
|